Showing papers on "Bark published in 1997"

In Vitro and in Vivo Antiplasmodial Activity of Cryptolepine and Related Alkaloids from Cryptolepis sanguinolenta

Abstract: Three different extracts and four alkaloids from the root bark of Cryptolepis sanguinolenta have been assessed in vitro against Plasmodium falciparum D-6 (chloroquine-sensitive strain), K-1, and W-2 (chloroquine-resistant strains). Cryptolepine (1) and its hydrochloride (2), 11-hydroxycryptolepine (3), and neocryptolepine (5) showed a strong antiplasmodial activity against P. falciparum chloroquine-resistant strains. Quindoline (4) was less active. The highest activity was obtained with compound 1. In vivo tests on infected mice showed that crytpolepine (1), when tested as its hydrochloride (2), exhibited a significant chemosuppressive effect against Plasmodium berghei yoelii and Plasmodium berghei berghei, while 1 had the same effect against P. berghei yoelii only. Compounds 3 and 4 did not show activity in this in vivo test system.

Fire resistance and bark properties of trees in a seasonally dry forest in eastern Bolivia

Abstract: As forest fragmentation and intentional burning of grasslands increase, the frequency of fires penetrating the dry and subhumid tropical forests of Bolivia is also likely to increase. To expand our understanding of the role of fire in tropical dry forest, the physical and thermal properties of barks of tree species were studied to determine their relative resistances to cambial damage by fire. For 16 tree species found in the dry forest of the Lomerio region of eastern Bolivia, bark thickness, moisture content, and specific gravity were measured. Insulating capabilities of bark were measured by obtaining cambial and surface temperatures during experimental wick fires. Bark thickness on trees 5-100 cm dbh (diameter at 1.4 m) ranged from 2–51 mm and both thick- and thin-barked species were represented. For all species, bark thickness increased as stem diameter increased. Bark thickness explained more (63%) of the variation in peak cambial temperatures during fires than did bark moisture content (4%) or specific gravity (1%). A threshold bark thickness of 18 mm was associated with the ability to withstand lethal cambial temperatures during the experimental, low intensity fires. For 13 of the 16 species included in this study, trees ≤20 cm dbh have bark thickness below the threshold 18 mm and, therefore, are likely to experience cambial injury from low intensity fires. Our results suggest that the forest presently characteristic of the Lomerio region did not develop with frequent fires and that species composition is likely to be substantially affected by an increase in fire frequency.

Disruption of Semiochemical-Mediated Aggregation in Bark Beetles

Abstract: Bark beetles (Coleoptera Scolytidae) are major worldwide pests, from the comfortable country towns of southern England (Greig and Gibbs 1983) to the remote eastern Himalayas in Bhutan (Schmutzenhofer 1988). They cause immense losses of killed timber—for example, 5 x 106 m3 of Norway spruce killed by the spruce bark beetle, Ips typographus, in Norway during the 1970s (Bakke 1989) and an estimated 96 x 106 m3 of lodgepole pine killed by the mountain pine beetle, Dendroctonus ponderosae, in British Columbia from 1972 to 1985 (Borden 1990). It is therefore not surprising that much research has been done on developing strategies and tactics for the management of bark beetles. In the latter three decades of this century, most of this research has involved the use of semiochemicals (Borden 1993).

Recovery of copper through decontamination of synthetic solutions using modified barks

Abstract: Decontamination of synthetic acetate, chloride, nitrate, and sulfate solutions containing 10, 100, 1,000, 10,000, and 50,000 ppm of copper using chemically treated barks has been studied. Metal percentage removal from solutions depends on the pH, the initial concentration, and, to some extent, the anion. It varies from 40 through 99 pct of the initial metallic ion’s content in the solution. The average retention capacity of the treated bark is about 43 mg of Cu/g of dry modified bark (0.68 mmole/g of dry bark). Extraction of copper cations from the saturated modified bark was made possible with dilute acid. Regeneration of bark for reuse as an ion exchanger was possible. Bark loaded with copper was analyzed by scanning electron microscopy (SEM) and infrared (IR) spectroscopy. Copper was uniformly distributed in the bulk of the bark. No copper segregation was observed. It seems that copper was bound to the acidic (phenolic) sites of the bark. Anions were not detected on the copper-loaded bark with either SEM electron probe microanalysis or IR spectroscopy. Incineration of the bark loaded with copper resulted in ashes containing about 77 pct of copper oxides, while pyrolysis of the same sample led to ashes containing 10 pct of metallic copper and about 85 pct carbon.

Passive monitoring of trace elements by means of tree leaves, epiphytic lichens and bark substrate

Abstract: Total concentrations of Al, Cu, Fe, Hg, Mn, Mo and Zn in theepiphytic lichen Parmelia caperata, substrate bark andleaves of oaks (Quercus cerris and Q pubescens)from a background area in Tuscany (central Italy) werecompared The elemental composition of unwashed samples,especially bark, was clearly affected by soil dustcontamination, thereby leading to incorrect interpretations ofbaseline concentrations and relationships between elementsThe normalization of total element concentrations to thesurface soil composition (digested and analyzed by the sameprocedures), using Al as reference element, gave more reliablebaseline values and allowed comparison between differentbiomonitors The suitability of lichens, leaves and barks forstudying the environmental distribution of trace elements interrestrial ecosystems is discussed

Baseline concentrations of copper and zinc in shoot tissues of a range of Salix species

Abstract: Background concentrations of Cu and Zn in bark, leaves, twigs and wood of eight species of Salix (willow) growing on the same soil type were investigated. It was found that the concentrations of Cu and Zn varied between plant parts and between species. There was no consistent pattern of metal concentration. Copper concentrations decreased in the order twigs > leaves > wood > bark, and those of Zn in the order leaves > bark > twigs > wood. The eight species did not show a common uptake pattern for the two metals. S. × sericans and S. cinerea had high concentrations of both metals; S. purpurea had high concentrations of Zn but low concentrations of Cu, whilst S. fragilis and S. viminalis had low concentrations of both metals. Concentration factors for both elements in shoot tissues were consistent, despite the variations in associated metal concentrations. A general trend of exclusion of Cu and concentration of Zn was evident. More Cu than Zn was fixed in woody tissue.

Constituents of the Bark of Ficus microcarpa Lf.

Abstract: The isolation and identification of twenty-eight crystalline components from the bark of Ficus microcarpa L.f. are described. Their structures were determined on the basis of spectral data and values taken from the literature. These compounds include fourteen triterpenoids, one fatty alcohol, eight steroids, one coumarin, one flavane, two 4-hydroxybenzoates, and one carotenoid-like compound.

Anti-mycobacterial screening of British Columbian medicinal plants

Abstract: One hundred methanol plant extracts were screened for antibiotic activity against Mycobacterium tuberculosis and Mycobacterium avium. Nineteen extracts exhibited some activity against M. tuberculosis and 16 extracts showed some activity against M. avium. Thirteen of these 19 active extracts were traditionally used by First Nations peoples to treat tuberculosis. Extracts made from Heracleum maximum (Umbelliferae) roots, Moneses uniflora (Ericaceae), aerial parts, and Oplopanax horridus (Araliaceae) inner bark completely inhibited the growth of both organisms at a concentration equivalent to 20 mg dried plant material/disc. Extracts of Alnus rubra (Betulaceae) bark and catkins, Empetrum nigrum (Empetraceae) branches, Glehnia littoralis (Umbelliferae) roots, and Lomatium dissectum (Umbelliferae) roots completely inhibited the growth of both M. tuberculosis and M. avium at a concentration equivalent to 100 mg dried plant material/disc.

Removal and recycling of copper from aqueous solutions using treated Indian barks

Abstract: Removal of copper from aqueous solutions containing 100–1000 ppm, using different Indian bark species, was performed on laboratory scale. The percentage removal of metal ions depends on the solution pH, bark species and time. The efficiency of copper removal by the used raw barks increases with a rise of solution pH and reaches a maximum of about 65–78% around pH 4–5. However, the decontaminated aqueous solutions were colored due to the dissolution of soluble organic compounds contained in the raw bark. This increases the biological and chemical oxygen demand (BOD and COD) of the solutions as well as the total organic carbon content (TOC). For this reason, raw bark should be treated either by chemical or biological means. Such treatment will allow the extraction of the soluble organic compounds and increase the chelating capacity and efficiency of the treated bark. Depending on the pH value, the chelating efficiency of treated barks is about 1.2–2.2 times that of the raw ones. Moreover, the retention capacity of the Indian treated bark varies from about 42–51 mg/g of dry bark. It is equal to or higher than that of common European species. About 1.8 mols of H3O+ are released, by the treated barks, for every mol of chelated copper ions. Moreover, scanning electron microscopy (SEM) observations show uniform distribution of metal ions throughout the copper saturated bark. Infra red (IR) spectra suggest that the copper ions are chelated to hydroxyl and/or carboxyl functional groups of organic compounds contained in the treated bark. It seems that the interaction of the copper ions with the bark follows a cation exchange mechanism. This hypothesis is supported by elution experiments that allow recovery of about 99% of the contained copper. The retention capacity of the treated bark is almost constant after five cycles of chelation–elution, suggesting that the `life time cycle' is sufficiently long for continuous industrial application. The spent copper loaded barks can either be incinerated or pyrolysed. It generates solids containing either ≈80% of CuO or ≈14% of Cu°, respectively. Such materials can be used either in the secondary or primary copper production, thus offering a friendly environmental solution of effluents' treatment. The suggested process can be used as an alternative to the classical technologies for effluent decontamination. It is also efficient for polishing effluents treated by other methods.

Tannin Composition of Eucalyptus camaldulensis, E. globulus and E. rudis. Part I. Wood

Abstract: In this work, a study on tannins (proanthocyanidins and ellagitannins) is carried out in bark extracts from different Eucalyptus species grown in Spain : E. camaldulensis, E. globulus and E. rudis. The tannin analysis was carried out using HPLC and classical chemical methods. Bark extracts were characterized by the abundance of polymeric proanthocyanidins and by the diversity of ellagitannins, The ellagitannins composition was related with the species and the tree provenance, allowing to discriminate E. globulus from E. camaldulensis and E. rudis.

Chemical composition of the volatile oil from the fruits of Cinnamomum zeylanicum Blume.

Abstract: GC and GC-MS analyses were used to characterize volatile oil composition of fruits of Cinnamomum zeylanicum (cinnamon) grown in 2 regions of South India, i.e. (i) coastal Karnataka and (ii) south Kerala. Results are tabulated. In both oils the major peak area was identified as trans-cinnamyl acetate, followed by beta-caryophyllene, peak area being 42.4 and 13.7%, respectively, in (i), vs. 54.2 and 9.2% in (ii). Levels of several other constituents were significant in both samples, e.g. 3-phenylpropyl acetate, cinnamyl alcohol, T-cadinol, benzyl benzoate, alpha-copaene, alpha-humulene and trans-cinnamaldehyde. In (i) 34 components were identified, vs. 31 in (ii). Essential oil from the fruits was distinct from that isolated from other parts of the plant, e.g. leaf, root bark and stem bark.

On the Distribution and Transport of Mineral Elements in Xylem, Cambium and Phloem of Spruce(Picea abies[L.] Karst.)

Abstract: The distribution of calcium, magnesium and potassium in the cambial region of a 20-year-old Norway spruce was determined by optical emission spectrometry (ICP-OES) in tissue samples ranging from the outer bark up to latewood and earlywood of the outer tree-rings. The highest contents of magnesium and potassium were found in the cambium and, in the case of calcium, in the developing phloem. In more detail we investigated the distribution and incorporation of calcium, magnesium and potassium in a model system of intact two-year-old plants (Picea abies [L.] Karst.). The roots of the seedlings, grown under controlled conditions, were removed from the soil and exposed to labelling solutions containing the enriched stable isotopes 25 Mg, 41 K, and 44 Ca as tracers. After seven days of labelling the cell walls of earlywood, latewood, cambium and phloem were analysed in stem cross sections of shock-frozen, cryo-substituted tissue by three microprobes: (i) by energy dispersive x-ray analysis (EDXA, 0.3 μm lateral resolution), (ii) isotope specific point analysis, using the laser microprobe mass analyser (LAMMA, 1.5μm lat. res.) and (iii) isotope specific imaging by secondary ion mass spectrometry (SIMS, 1-3μm lat. res.). After seven days of labelling approximately 60-75% of the Ca-content, 5-65% of the Mg-content and about 25-30% of the K-content within the cell walls of the shoot originated from the labelling solutions. The upper part (one-year-old) of the shoot axis contained a 10% smaller fraction of labelled Ca and a 10% larger fraction of labelled Mg in comparison to the more basal regions of the shoot (two-year-old). For all three elements we could not detect any significant radial gradient of the labelled fraction while comparing earlywood, latewood, cambium and phloem. We interpret our results as evidence for (i) a relevant bidirectional longitudinal transport and (ii) a radial element exchange between xylem, cambium and phloem, completed within the seven days of labelling.

Tree bark as a bioindicator of air pollution in Navarra, spain

Abstract: During a two year research period from 1992 to 1993, samples of different species of trees were taken in 17 forest stands located in Navarra, Spain. From these samples, bark extracts were prepared in which the pH and the conductivity were measured. The health of the sampling trees was also evaluated by determining the degree of defoliation and decoloration of the canopies. The bark tissue analysis revealed the presence of an environmental acidity gradient that decreased from NW to SE. This coincides with the location of important sources of pollution and their course of transport and dispersion. On the other hand, in the samples ofQuercus ilex a significant correlation between the pH and the defoliation levels (P≤0.01, r=0.62) was found. This fact reveals the potential usefulness of tree bark as a health bioindicator of trees.

Two New Isoflavones from the Bark of Ficus microcarpa

Abstract: Two new isoflavones, ficuisoflavone (1) and isolupinisoflavone E (2), were isolated from the bark of Ficus microcarpa L.f.. Their structures were principally elucidated by spectral methods.

Indonesian medicinal plants. XXI. Inhibitors of Na+/H+ exchanger from the bark of Erythrina variegata and the roots of Maclura cochinchinensis.

Abstract: Through bioassay-guided separation of the methanol extracts of Indonesian medicinal plants, three inhibitors of the Na+/H+ exchange system, erythrinin B (2), euchrenone b10 (3), and 1,3,5-trihydroxy-4-(3-methylbut-2-enyl)xanthen-9-one (4), were isolated from the bark of Erythrina variegata (Fabaceae) (for 2) and the roots of Maclura cochinchinensis (Moraceae) (for 2, 3, 4). Compounds 2, 3, and 4 significantly inhibited the Na+/H+ exchange system of arterial smooth muscle cells, with minimum inhibitory concentrations of 1.25, 1.25, and 10 micrograms/ml, respectively. Three new prenylated xanthones named isocudraniaxanthones B (5) and A (7) and isoalvaxanthone (9) were also isolated from M. cochinchinensis and the chemical structures were elucidated on the bases of their chemical and physicochemical properties.

Relative value of slow-canker growth and bark reactions as resistance responses to white pine blister rust

Abstract: (1997). Relative value of slow-canker growth and bark reactions as resistance responses to white pine blister rust. Canadian Journal of Plant Pathology: Vol. 19, No. 4, pp. 352-357.

Carbon isotopic composition of legumes with photosynthetic stems from mediterranean and desert habitats.

Abstract: The carbon isotopic compositions of leaves and stems of woody legumes growing in coastal mediterranean and inland desert sites in California were compared. The overall goal was to determine what factors were most associated with the carbon isotope composition of photosynthetic stems in these habitats. The carbon isotope signature (d13C) of photosynthetic stems was less negative than that of leaves on the same plants by an average of 1.51 ± 0.42 ;pp. The d13C of bark (cortical chlorenchyma and epidermis) was more negative than that of wood (vascular tissue and pith) from the same plant for all species studied on all dates. Desert woody legumes had a higher d13C (less negative) and a lower intercellular CO2 concentration (Ci ) (for both photosynthetic tissues) than that of woody legumes from mediterranean climate sites. Differences in the d13C of stems among sites could be entirely accounted for by differences among site air temperatures. Thus, the d13C composition of stems did not indicate a difference in whole-plant integrated water use efficiency (WUE) among sites. In contrast, stems on all plants had a lower stem Ci and a higher d13C than leaves on the same plant, indicating that photosynthetic stems improve long-term, whole-plant water use efficiency in a diversity of species.

White spruce resistance to white pine weevil related to bark resin canal density

Abstract: Examination of the bark from the uppermost lateral branches of white spruce, Picea glauca (Moench) Voss, indicated that trees resistant to attack by the white pine weevil, Pissodes strobi Peck, had...

The influence of four different predators on bark beetles in European forest ecosystems (Coleoptera: Scolytidae)

Abstract: Field and laboratory work was carried out to study the possible impact of 4 different species of bark beetle enemies. These are Scoloposcelis pulchella Zetterstedt 1838 [Heteroptera: Anthocor -idae], Thanasimus formicarius Linnaeus 1758 [Coleoptera: Cleridae] Nemosoma elongatum Linnaeus 1761 [Coleoptera: Ostomidae] and Medetera dendrobaena Kowarz 1877 [Diptera: Do-lichopodidae]. These species are preying upon many bark beetles. The main prey species of N elongatum and Mdendrobaena are Pityogenes chalcographus Linnaeus 1758 [Coleoptera: Scolytidae] and Taphrorychus bicolor Herbst 1793 [Coleoptera: Scolytidae], S pulchella mainly attacks P chalcographus. On spruce the bark beetle Ips typographus Linnaeus 1758 [Coleoptera: Scolytidae] is one of the most important prey species of T formicarius. The predator and the bark beetle species were reared in the laboratory to gain information about their biology. The Scolytidae were also reared to provide an adequate food supply for the predators. In the laboratory, the egg production of the predator species and the prey consumption during their larval development were determined. Furthermore, the densities and the voltinism of the antagonists and of the bark beetles were investigated. Calculations to estimate the predator capacity of the 4 antagonistic species were performed. Based on this data the role of S pulchella, T formicarius, N elongatum and N dendrobaena in bark beetle regulation is discussed.

The effect of larval aggregation behaviour on larval growth of the spruce bark beetle Dendroctonus micans

Abstract: 1. The great spruce bark beetle Dendroctonus micans is a primary pest of spruce in Europe. It is unusual among Eurasian scolytids in that apparently healthy trees are attacked by solitary adults, but larvae feed en masse, in response to a larval aggregation pheromone. 2. The effect of brood size on larval growth was determined in experiments on detached bark, logs and living trees. A positive relationship was found between brood size and larval growth in experiments started with either eggs or larvae up to fifth instar. The relationship appeared to be independent of the effects of both preformed and induced defences in bark. 3. No evidence was found to support the hypothesis that larvae feeding in groups spend a greater proportion of time feeding. Addition of resin to egg chambers in detached bark pieces resulted in high mortality of first-instar larvae. A possible role for larval aggregation in minimizing the effects of host defences is discussed.

Pogostol O-methyl ether and artabotrol: two novel sesquiterpenes from the stem bark of Artabotrys stenopetalus

Abstract: An investigation of the stem bark of Artabotrys stenopetalus (Annonaceae) has yielded two novel sesquiterpenes, the guaiane pogostol O-methyl ether and an isodaucane that we have named artabotrol, together with the known sesquiterpene β-caryophyllene oxide and the alkaloid artabotrine. The compounds were identified by detailed analysis of their spectral data.